1. Field of the Invention
The present invention relates in general to a steering column of a vehicle, more specifically, to a steering column having a variable impact-absorbing structure that varies absorption of the impact energy according to a physique of a driver, thereby minimizing an injury upon the driver.
2. Description of the Related Art
In general, a steering column of a vehicle is supported by an upper and a lower part of the body of a car. The upper support structure includes a tilt for tilt operation of the steering column, and the lower support structure includes a hinge for tilting the steering column as a whole.
During a collision, a driver is often bumped secondarily into the steering wheel, so the steering wheel should be designed to absorb secondary collision impact. Moreover, the steering column should be stopped from being pushed to the rear where the driver is seated even when the front of the car is crushed from the collision.
Therefore, at impact, the support structures of the steering column fixed to the body of the car are designed to help the steering column make a relative movement to the body of the car. This can be realized by building the steering column to make a relative movement from its support structures at impact, or designing the support structures and the steering column as one body so that they move together relative to the body of the car.
Particularly, U.S. 2002/0167157 A1 disclosed an impact-absorbing structure having a metal strap that causes plastic deformation as the steering column and the body of a car move relative to each other during a car crash.
In the disclosure, the impact-absorbing structure includes a steering column on which a steering shaft is rotatably mounted in the circumferential direction, a supporter for supporting the steering column to the body of a car, and an energy absorber mounted on at least one of the steering column and the body of the car in order to vary absorption of the impact energy, depending on whether a driver wears a seat belt or not.
However, the above impact-absorbing structure was designed to adjust the energy absorption depending on whether the driver wears a seat belt, and it was not necessarily built in consideration with weight of the driver or physical conditions of the driver in different postures. Therefore, there was a limit to protect the driver from injuries as much as possible.
Moreover, the structure of the variable impact energy absorbing device was so complicated that overall process or assembly was very difficult to carry out. This resulted in low productivity and disappointing profits.
In addition, the energy absorber itself was composed of one strap in a band shape, so it could not get various strain energies, and this eventually turned collision related tuning to its own physical property.